Posts Tagged ‘simulations’
Simulation Suggests There May Have Been a Fifth Gas Giant in Our Solar System
The formation of Uranus and Neptune has puzzled astronomers for years. The assumed disc of gas and dust that formed the two gas giants would have been too thin at their current locations to form the icy planets. It’s more likely that the two, and Jupiter and Saturn, were closer together in the earlier days of our solar system, and spread out once the disc was depleted. The “five great gravitational bullies of the solar system, Jupiter, Saturn, Uranus and Neptune” jockeyed for position after being formed. According to past simulations, which only included the current planets, either Uranus or Neptune at least should have been jettisoned into deep space. “People didn’t know how to resolve that,” says David Nesvorny of the Southwest Research Institute. He offers a new explanation: “A sacrificial ice giant between Saturn and Uranus.”
The existence of this new planet, who some of Nesvorny’s colleagues are calling Hades, is supported by the results of 6,000 computer simulations. Previous simulations only included Jupiter, Saturn, Uranus and Neptune in the outer solar system. But these new simulations also included models with five planets, testing different starting position scenarios. In 90 percent of the four planet models, the simulations ended with only three planets left in the outer system. But in half of the five planet simulations, four planets in very similar positions to our current solar system resulted. The results with the most similar positions started with a fifth planet between Saturn and Uranus, and ended with this planet cast out after an encounter with Jupiter.
These results also suggest that Jupiter “jumped” to its current position from one that was closer to the sun. This occurred in the simulations that allowed the four inner planets, including Earth, to survive the clash of the gaseous titans. “This jumping Jupiter theory is very difficult to achieve for the four-planet system. But it’s a natural consequence of the five-planet system,” says Nesvorny.
The planetary battle could also explain the heavily cratered surface of the moon caused during the “late heavy bombardment.” The Kuiper Belt and Oord Cloud were not fully formed, and the disturbance could have flung debris from these regions of proto-planets beyond Neptune towards the inner system.
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Supercomputer Simulation Shows for the First Time How a Milky Way-Like Galaxy Forms
Check all galactic bulges at the door
That doubt arose from the fact that when previous, lower-resolution models were run based on that cosmological model, a huge central bulge emerged in the galaxy--a bulge that is absent from all but the center of the Milky Way (another way of saying that: there was more bulge and less disc, whereas the Milky way is more disc, less bulge). This had some physicists thinking that perhaps there was a flaw in the cosmological model itself, which seemed incapable of producing via simulation the flat, spiral-armed qualities consistent with observations of our galaxy.
But the problem wasn’t with the model, it turns out, but with the simulation of star formation. In reality, star formation happens in clusters, where dense clouds of gas feed the process of star birth in fairly tightly defined regions. But in low-resolution simulations(resolution in this sense means the ability to track individual particles), gas densities tended to spread out over relatively large areas, showing stars forming throughout the galaxy rather than in clusters. This led to a larger galactic bulge--and a less accurate picture of how Milky Way-like galaxies came into being.
To get the high resolution necessary to make the model work took a great deal of computing power, including 1.4 million processor-hours on NASA’s Pleiades supercomputer as well as additional time on supercomputers at UC Santa Barbara and the Swiss National Supercomputing Center. And at the time, the researchers had no idea if their added resolution would really make a difference.
It turns out it did. The simulated galaxy, Eris, shares the shape, bulge-to-disk ratio, star content, brightness, and various other characteristics with the Milky Way, demonstrating that the “cold dark matter” model can produce spiral-armed disc galaxies like the one we call home after all.
Oak Ridge Labs Using World’s Fastest Supercomputer to Model Next-Gen Nuclear Plants
The Nuclear Science and Technology Division at ORNL has long been charged with integrating nuclear energy models with national security simulations and other data to solve specific problems in the nuke energy field. But though their previous efforts were state-of-the art from a computer-modeling standpoint, the models were still disjointed -- one software package might examine the reactor core, another model would simulate security fail-safes or the disposal of spent fuel.
From Denovo they wanted one model that contained everything in one sim. For that, they would have to bring out the Jaguar.
ORNL researchers first tried adapting older programs to the larger models, but they quickly abandoned the idea because those programs simply didn't take advantage of ORNL's computing capabilities. Oak Ridge is home to Jaguar, the , so the team developing Denovo sculpted the software specifically to take advantage of the massive processor and memory power at their disposal.
Tapping such power has allowed the team to simulate entire nuclear facilities -- reactor cores as well as auxiliary buildings, and even the ITER fusion reactor -- with degrees of accuracy once unobtainable. More accurate models mean better safety mechanisms, reduced cost, and better efficiency from the next generation of nuclear power plants. More importantly, it means that next-gen nuclear should arrive much sooner as reliable models save engineers the time, energy, expense, and potential disaster of a trial and error approach to reshaping America's energy infrastructure.
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IBM’s City Simulation Trains Planners to Tackle Future Problems for Growing Urban Centers
OK, mayor, 40 percent of your water supply is leaking out ... what do you do?
The company unveiled its "serious game" this week at the IMPACT 2010 conference in Las Vegas, as a training tool for city leaders and planners. The free game would require players to guide their city through sector-specific missions focused on energy, water, banking, and retail.
One mission involves the water usage increasing at twice the population growth. The city is also losing as much as 40 percent of its water supply through leaky infrastructure, and energy costs are rising. Players would need to put a water management system in place that draws on "accurate real-time data" to make their decisions.
IBM pointed to expert predictions that the world's urban populations will double by 2050, with an estimated one million people moving into cities each week. Today's cities already consume 75 percent of the world's energy, emit more than 80 percent of greenhouse gases, and lose as much as 20 percent of their precious water because of infrastructure leaks.
Simulations are already used as tools for real-world planning among financial analysts and the . But games such as CityOne could represent a stepping stone to the far more ambitious projects such as Europe's proposed which would incorporate reams of real-time data about the world.
Either way, we're just waiting for the Hollywood story where the young genius with knack for urban planning suddenly realizes that he's been "playing" not just a game, but real life all along.
Europe’s Living Earth Simulator Could Forecast the Future
The goal would require gathering unprecedented amounts of information about the planet and its societies
Such "reality mining" would track everything from financial transactions to individual travel itineraries, from medical records to carbon dioxide emissions. If computer modelers can pull off the feat of simulating not only the planet's systems but also every one of its inhabitants, it could potentially lead to simulating the future in a way similar to how weather forecasters predict the weather.
That astounding vision is the brainchild of Dirk Helbing at the Swiss Federal Institute of Technology in Zurich. Helding's desire for such real-time knowledge of the Earth stems from his leadership in the emerging field of techno-socio-economic studies, and perhaps reading a bit much of Isaac Asimov's Foundation series and dreaming of psychohistory's predictive powers.
Plenty of supercomputers already run complex simulations focused on financial markets . NASA has also joined forces with Cisco to launch a $100 million network that integrates all sorts of ground, sea, air and space sensors -- perhaps a bit of a precursor to what Helding has in mind.
That's not to say that the project might not need a heck of a lot more money than $1.3 billion, assuming that the European Commission approves it. But Technology Review suggests that the alternate to a publicly funded effort is a darker vision of such predictive power in the hands of a single corporation, or perhaps one nation's military. In that spirit, we'd suggest that there's no time like now to start -- hopefully any such model incorporates the zoom and swoop options available in Google's engine.
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